First of all you have to open up bee2 and get the Door and Auto portal into your pallet
after that step you can export it to portal 2 and launch the game

Now that you exported the pallet into the game with bee2 and launched the game
its time to make a new chamber which i hope you already know how to do
if not then just poke around in the community chambers tab and you will find it eventually

now you go to a random place (the floor) and press + once and you get a block

Now that you got a block in the chamber place an auto portal onto the block and make sure it has "start enabled" active (or just a button connected to it) because the portal must be active to work

Now after you placed the auto portal this would be the final step for the broken portal
first of all you place a door infront of the auto portal and make it go fully infront leave no gaps
oh and make sure it has "start enabled" active so the door is open (just like the auto portal a button of some kind will work too)

congrats you just made a weird portal that can do weird things

how to know it worked: if instead of the portal there is just the outline (and the actual portal randomly in a corner) then it worked

i would recommend that you place another auto portal somewhere that has "Start enabled" active
or you can redo all of that but with a diffrent portal color

this was all tested in the portal 1 theme so it might not work in other themes

i recorded a video of the portal whilst i wanted to make a map and not this

before i forget here is the link to download bee2
https://github.com/BEEmod/BEE2.4
use the 4.36.1 release (which i use)
if you use any newer releases you will get a build error upon launching the map